Vardaan Learning Institute

Ans: (b) Synapse
The small gap between two neurons where the nerve impulse passes is called synapse.

Ans: (c) Cytokinin
Cytokinins promote cell division.

Ans: (c) inhibit growth
It is a stress hormone responsible for wilting of leaves.

Ans: (d) Chewing
Chewing is a voluntary action controlled by our will, unlike the others which are involuntary.

Ans: (b) Thyroxin
Iodine is essential for the synthesis of thyroxin by the thyroid gland.

Ans: (a) Phototropism
Growth movement in response to light is phototropism.

Ans: (b) Medulla
Spinal cord is the downward continuation of the Medulla Oblongata.

Ans: (c) Pancreas
Pancreas secretes enzymes (exocrine) and hormones like insulin (endocrine).

Ans: (b) Gustatory receptors
Gustatory receptors detect taste; Olfactory detect smell.

Ans: (b) Cranium
The brain is protected by the skull or cranium.

Ans: (d) A is false but R is true.
A is false because CNS includes Brain AND Spinal Cord. R is true.

Ans: (a) Both A and R are true and R is the correct explanation of A.
Synapses ensure one-way transmission because neurotransmitters are only released from the axon ending.

Ans: (b) Both A and R are true but R is not the correct explanation of A.
Insulin regulates blood sugar by signaling cells to absorb glucose. Diabetes is the result of failure, not the reason for regulation.

Ans: (a) Both A and R are true and R is the correct explanation of A.
Plants lack nerve cells but use electro-chemical signals to communicate triggers for movement.

(i) (Diagram required: Cell Body/Soma, Axon (long tail), Dendrites (branching from soma)).
(ii) Dendrite: Acquires the information (impulse) from the previous neuron/receptor.

Reflex Arc: The pathway taken by a nerve impulse during a reflex action.
Stimulus $\rightarrow$ Receptor $\rightarrow$ Sensory Neuron $\rightarrow$ Spinal Cord (Relay Neuron) $\rightarrow$ Motor Neuron $\rightarrow$ Effector (Muscle) $\rightarrow$ Response.

When a tendril touches a support, auxin diffuses to the side away from the support. This causes cells on the other side to grow faster than the side in contact, causing the tendril to bend around the support (Thigmotropism).

Tropic: Directional movement (Growth related). e.g., Phototropism (shoot bends to light).
Nastic: Non-directional movement (Not growth related). e.g., Thigmonasty (Touch-me-not plant folding leaves).

Process: When light falls on one side of shoot, auxin diffuses to the shady side. High auxin conc. stimulates faster cell growth on shady side, causing shoot to bend towards light.
(Diagram showing bending towards sun).

Hormone: Adrenaline (Adrenal gland).
Function (Emergency): Increases heart beat, diverts blood to muscles, increases breathing rate to supply more oxygen for energy (Fight or Flight response).

(i) (Diagram required: Forebrain (Cerebrum), Midbrain, Hindbrain (Pons, Medulla, Cerebellum)).
(ii) (a) Cerebellum: Posture, balance, precision of voluntary actions.
(b) Medulla: Involuntary actions like BP, salivation, vomiting.
(c) Cerebrum: Thinking, memory, sensory interpretation, voluntary control.

(i) Thyroid: Thyroxin (Metabolism of carbs, fats, proteins).
(ii) Pituitary: Growth Hormone (Regulates growth and development).
(iii) Pancreas: Insulin (Regulates blood sugar level).
(iv) Adrenal: Adrenaline (Fight or flight response).
(v) Testes: Testosterone (Male secondary sexual characters).

(i) Insulin.
(ii) Pancreas.
(iii) Feedback Mechanism: When blood sugar rises, pancreatic cells detect it and secrete more insulin. As sugar level falls, insulin secretion is reduced. This ensures precise regulation.

(i) Sudden, involuntary response to a stimulus.
(ii) Receptors in sense organs (e.g., skin).
(iii) Reflex arcs evolved because the thinking process of brain is not fast enough to respond to dangerous stimuli to prevent injury.